In the manufacturing of many types of products, it is often necessary to reflow a predeposited stripe of solder to effectuate a bond between a base element and an overlaying element. This manufacturing requirement is often encountered in the production of printed circuit boards where presoldered leads arrayed in a row are solder bonded to contact pads on a printed circuit board. One common procedure utilized consists of moving heated rams and an interposed nonsolder wettable spring blade holddown onto a row of presoldered leads to reflow the solder, whereafter the heated ram is withdrawn while the holddown acts to hold the leads while the solder solidifies.
Other solder reflow procedures, such as shown in U.S. Pat. No. 4,306,674, issued Dec. 22, 1981 to J. L. Charles, et al., include passing an assemblage of first and second elements and interposed solder through a nip of a first pair of heating rollers and then through a nip of a second pair of cooling rollers. In this apparatus the first rollers press and heat the solder, and the second rollers act to hold and cool the articles while the solder solidifies. In another procedure, such as shown in U.S. Pat. No. 3,941,292, issued Mar. 2, 1976 to A. A. Osipov, flat presoldered leads of a microcircuit are bonded to sites on a printed circuit board by relatively displacing the board with respect to a heated soldering element which individually engages each of a succession of leads to effectuate a reflow of the solder so that each succeeding engaged lead is solder bonded to the circuit board.
In these prior procedures, contact must be maintained between the presoldered elements and the heating elements for a sufficient time to enable solder to be heated to the required melting temperature, thus substantially limiting the speed of operation. In order to increase the speed of operation of these types of prior art devices, it is necessary to contact the presoldered elements with heating elements that are heated well above the temperature required to melt the solder to insure the application of sufficient heat during a relatively short period of contact with the presoldered elements. Use of such high temperatures, often results in an increase in damage due to thermal shock or damage to heat sensitive components mounted at other adjacent areas on the circuit board.